The perimeter of a triangle is the sum of the lengths of its sides:

p = x + y + z
p = 5cm + 13cm + 5cm = 23cm

The first step to solve a quadratic expression that's not set to zero is to solve the equation so that it is set to zero:

c² + c - 38 = -c - 3
c² + c - 38 + 3 = -c
c² + c + c - 35 = 0
c² + 2c - 35 = 0

Next, factor the quadratic equation:

c² + 2c - 35 = 0
(c - 5)(c + 7) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (c - 5) or (c + 7) must equal zero:

If (c - 5) = 0, c must equal 5
If (c + 7) = 0, c must equal -7

So the solution is that c = 5 or -7

To factor a quadratic expression, apply the FOIL method (First, Outside, Inside, Last) in reverse. First, find the two Last terms that will multiply to produce 5 as well and sum (Inside, Outside) to equal -6. For this problem, those two numbers are -5 and -1. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² - 6y + 5
y² + (-5 - 1)y + (-5 x -1)
(y - 5)(y - 1)

A cube is a rectangular solid box with a height (h), length (l), and width (w). The volume is h x l x w and the surface area is 2lw x 2wh + 2lh.

To multiply binomials, use the FOIL method. FOIL stands for First, Outside, Inside, Last and refers to the position of each term in the parentheses.